Silver halide color photographic material are characterized in that they may form high-quality images and are economically advantageous. They are most popularly used to reproduce color images. In order to further improve the characteristics of such silver halide color photographic materials, various studies have been and are being made to obtain more improved high-quality color images. To improve the image quality of color images to be formed on color printing materials, it is required that the color reproduction of the color prints obtained after development is good, that the color images formed are sharp and are not blurred (that is, the sharpness of the color images formed is high) and that the fine dye grains constituting the color images formed are negligible with the naked eye (that is, the graininess of the color images formed is fine). In addition, it is also desired that the color images formed are fast to light, heat and moisture and are therefore not faded for a long period of time. In particular, the color fastness is an important factor to photographic color images. Recently, noticeable improvements have been made in the color fastness of photographic color images and storage of color prints for a long period of time has become possible.
The most popular method for producing color images on silver halide color photographic materials is such that couplers in the material are reacted with an oxidized, aromatic primary amine-type color developer to form indophenols, indanilines, indamines, azomethines, phenoxazines, phenazines and the like dyes. According to the method, color images are reproduced by a subtractive color process. According to this, in general, color images are formed by varying the amounts of three dyes of yellow, magenta and cyan to be formed.
As yellow couplers of such couplers, pivaloyl yellow couplers and benzoyl yellow couplers have heretofore been used most popularly. However, the former have a drawback that their coloring properties are poor, though the color images formed from them are fast. Therefore, their use is limitative in that they could not fully satisfy the essential requirements in these days requiring rapid processing of photographic materials while reducing the amount of replenishers to the processing solutions. In addition, the former are not on a sufficiently satisfactory level with respect to the color hue of the color images to be formed therefrom. On the other hand, the latter have serious drawbacks in that the color hue of the color images to be formed from them is much poorer than that from the former; though their coloring properties are good, and that the fastness of the color images formed from them is extremely low. For couplers for color prints, the color hue and the fastness of the dyes to be formed therefrom are considered important. In general, therefore, pivaloyl yellow couplers are used for color prints. However, pivaloyl yellow couplers are not still on a sufficiently satisfactory level with respect to the color hue of the dyes to be formed therefrom. Therefore, further improvements in them are desired.
Considering the current situation, pivaloylacetanilide couplers having an alkoxy group at the ortho-position of the anilido ring have been specifically noticed so as to further improve the color reproducibility in color prints. Such couplers have been surely improved with respect to their color reproducibility in some degree but still have problems in point of the fastness of the color images formed therefrom.
The problem common to pivaloyl couplers is that the fastness of the color images to be formed therefrom is not sufficient under high-humidity conditions. In addition, pivaloyl couplers are problematic in point of the fastness to light under high-humidity conditions. Since color prints are stored under varying conditions of light, heat and humidity, it is difficult to practically assess their fastness. Therefore, it is necessary to test color prints under various conditions.
Recently, to improve the color reproducibility and the coloring properties of couplers to form color images, for example, there have been proposed acylacetamide-type yellow couplers having 3-membered to 5-membered cyclic structures in European Patent EP 0,447,969A1, cyclic-structured malondianilide-type yellow couplers in EP 0,482,552A1, and dioxane-structured acylacetanilide-type yellow couplers in U.S. Pat. No. 5,118,599.
On the other hand, as compounds which may improve the storability of yellow color images, known are phenolic compounds with steric hindrance described in JP-A 60-222853 (the therm "JP-A" as used herein means an "unexamined published Japanese patent application"), polyalkylpiperidine compounds described in JP-A 59-11935, and compounds described in JP-A 2-300748. Combining these compounds and yellow couplers, the fastness to light of the color images formed may surely be improved. However, it has been found that such compounds worsen the coloring properties of the couplers combined with them.
Recently, bisphenols have been reported in EP 0,508,398A1 and phenol derivatives in JP-A 5-19427. Using these compounds together with couplers, the fastness to light of the color images formed can be improved in some degree only in their high density areas. In addition, the coloring properties of the couplers combined with these compounds are not worsened so much. However, even though these compounds are combined with couplers, the fastness to light of the color images formed cannot be improved on a satisfactory level in their low density areas.